Abstract: Toppling failure is one typical type of deformation failure modes of steep layered rock slopes. Analysis of toppling failure of rock slopes due to seismic loads possesses an important guiding significance for engineering design. Based on the limit equilibrium, a general analytical solution of block toppling failure due to earthquakes is presented for the condition that block slenderness is relatively large. In terms of cases with simple geometry, explicit expressions are given. The calculation formulas of the normal force between block interfaces, failure mode transition point and toe residual sliding force are obtained. The influence of seismic loads on the failure mode of counter-tilt rock slope, maximum allowable inclinations of the line normal to dip when toppling failure occurs, failure mode transition point and toe residual sliding force are studied through four typical examples. Those provide a theoretical foundation for the seismic support design of counter-tilt rock slopes. Finally, the comparative analysis of the analytical method and the transfer coefficient method is done according to the quantitative relationship between seismic influence coefficient, failure mode transition point and toe residual sliding force. The results show that the analytical method achieves sufficient accuracy when block slenderness is more than 20.

Key words: limit equilibrium, counter-tilt rock slope, toppling failure, seismic loads, residual sliding force